The invention relates to a class of block copolymers that form solutions that can reversibly gel under specific conditions.
Gels are polymer networks that can absorb solvents and thereby swell. For example, hydrogels are gels that swell in aqueous solutions. In general, gels fall into two categories. In crosslinked gels, the polymer chains that make up the networks are covalently bonded to each other. In physical gels, the polymer chains are attracted to each other by non-covalent forces (e.g., ionic, electrostatic, and/or van der Waals interactions).
Because the polymer chains of a physical gel are not chemically crosslinked, physical gels can have special properties. For example, physical gels can be highly responsive to physical stimuli such as temperature, pH, ion concentration, solvent polarity, or polymer concentration. The responsiveness can be manifest as swelling or shrinkage of the gel, changes in the shape of the gel, or changes in the viscosity of the gel. The gel can also undergo a reversible phase change between its gel and liquid states under appropriate conditions.
A class of physical gels that are of particular interest are the monodisperse gels. Monodisperse gels are made up of identical polymer chains of uniform size. Because each chain is of the same molecular weight, the spacing between structural elements is also of generally uniform size. By appropriate design, more direct control of pore size can be achieved in a monodisperse polymer system relative to a polydisperse system.